Hydrocracking of heavy feedstocks with improved hydrogen management

Abstract

An improved process for hydrocracking heavy petroleum feedstocks wherein hydrogen-containing streams associated with a hydrocracker are subjected to rapid cycle pressure swing adsorption having a cycle time of less than 30 S.

1. A process for hydrocracking a hydrocarbon feed, comprising:
 a) contacting a hydrocarbon feed in a hydrocracking zone with a hydrogen-containing gas and a catalytically effective amount of a hydrocracking catalyst under hydrocracking conditions thereby resulting in a lower boiling hydrocarbon liquid phase and a vapor phase containing hydrogen and light hydrocarbons; 
 b) separating the lower boiling hydrocarbon liquid phase and the vapor phase; 
 c) removing at least a portion of the light hydrocarbons from at least a portion of the vapor phase, thereby increasing its hydrogen concentration, in a rapid cycle pressure swing adsorption unit containing a plurality of adsorbent beds and having a total cycle time of less than about 30 seconds and a pressure drop within each adsorbent bed of greater than about 5 inches of water per foot of bed length; and 
 d) recycling at least a portion of the vapor phase of step c) above having an increased concentration of hydrogen to the hydrocracking zone; 
 wherein the removing step c) results in a recovery of a purified hydrogen-containing gas stream, relative to said hydrogen-containing make-up treat gas, said vapor phase product, or both, so as to exhibit (i) a rate of recovery (R%) greater than 80% for a product purity to feed ratio (P%/F%) greater than 1.1, (ii) a rate of recovery (R%) greater than 90% for a product purity to feed ratio (P%/F%) less than 1.1 but greater than 0, or (iii) both (i) and (ii). 
 
     
     
       2. The process of  claim 1 , wherein the hydrocarbon feed is selected from those boiling above about 350° F. (177° C.). 
     
     
       3. The process of  claim 2 , wherein the hydrocarbon feed is selected from the group consisting of naphtha boiling range feeds, kerosene boiling range feeds, and distillate boiling range feeds. 
     
     
       4. The process of  claim 3 , wherein the hydrocarbon fed is selected from the group consisting of Fischer-Tropsch liquids, lube stocks, raffinates, heavy naphthas, atmospheric gas oils, vacuum gas oils, deasphalted, vacuum, and atmospheric residua, hydrotreated or mildly hydrocracked residual oils, coker distillates, straight run distillates, solvent-deasphalted oils, pyrolysis-derived oils, high boiling synthetic oils, cycle oils and cat cracker distillates. 
     
     
       5. The process of  claim 2 , wherein the hydrocracking catalyst contains one or more components selected from the group consisting of cobalt, nickel, tungsten, alumina, a zeolite, silica, silica-alumina, and molecular sieve. 
     
     
       6. The process of  claim 5 , wherein the total cycle time is less than about 10 seconds and the pressure drop of each adsorbent bed is greater than about 10 inches of water per foot of bed length. 
     
     
       7. The process of  claim 2 , wherein the total cycle time of rapid cycle pressure swing adsorption is less than about 15 seconds. 
     
     
       8. The process of  claim 7 , wherein the total cycle time is less than about 5 seconds. 
     
     
       9. The process of  claim 6 , wherein the pressure drop of greater than about 20 inches of water per foot of bed length. 
     
     
       10. The process of  claim 9 , wherein the cycle time is less than about 5 seconds and the pressure drop is greater than about 20 inches of water per foot of bed length. 
     
     
       11. The process of  claim 10 , wherein a portion of the vapor phase is not treated in the rapid cycle pressure swing adsorption unit to remove light hydrocarbons and which portion is also recycled to the hydrocracking zone. 
     
     
       12. The process of  claim 6 , wherein the vapor stream is scrubbed with a basic scrubbing solution comprised of an amine prior to being conducted to the rapid cycle pressure swing adsorption unit. 
     
     
       13. The process of  claim 6 , wherein the rapid cycle pressure swing adsorption unit removes contaminants selected from the group consisting of CO 2 , water, ammonia, and H 2 S. 
     
     
       14. The process of  claim 1 , wherein the cycle time is less than about 10 seconds and the pressure drop is greater than about 10 inches of water per foot of bed length. 
     
     
       15. The process of  claim 1 , wherein said hydrogen-containing gas is comprised of a purified make-up gas produced from a hydrogen-containing make-up gas in a rapid cycle pressure swing adsorption unit containing a plurality of adsorbent beds and having a total cycle time of less than about 30 seconds and a pressure drop within each adsorbent bed of greater than about 5 inches of water per foot of bed length, wherein the purified make-up gas from the rapid cycle pressure swing adsorption unit is higher in hydrogen concentration than the hydrogen-containing gas. 
     
     
       16. The process of  claim 15 , wherein the hydrocarbon feed is selected from the group consisting of naphtha boiling range feeds, kerosene boiling range feeds, and distillate boiling range feeds. 
     
     
       17. The process of  claim 15 , wherein the cycle time is less than about 10 seconds and the pressure drop is greater than about 10 inches of water per foot of bed length. 
     
     
       18. The process of  claim 17 , wherein the cycle time is less than about 5 seconds and the pressure drop is greater than about 20 inches of water per foot of bed length. 
     
     
       19. The process of  claim 1 , wherein a portion of the vapor phase is not treated in the rapid cycle pressure swing adsorption unit to remove light hydrocarbons and which portion is also recycled to the hydrocracking zone. 
     
     
       20. The process of  claim 1 , wherein the hydrocracking process is shape selective, wherein the feed is selected from a distillate and a lubricating oil basestock and the pour point of the feed is reduced and the catalyst is comprised of a zeolite. 
     
     
       21. The process of  claim 1 , wherein the hydrocracking process is a shape selective distillate dewaxing, carried out at reaction conditions of 260 to 455° C., 20 to 50 kg/cm 2  hydrogen partial pressure, 1 to 2.5 LHSV, and 250 to 425 Nm 3 /m 3  hydrogen circulation rate wherein a lower sulfur, lower pour point distillate product is produced. 
     
     
       22. The process of  claim 1 , wherein the hydrocracking process is shape selective lube dewaxing, carried out at reaction conditions of 500 to 750° F, 400 to 2000 psi, 1500 to 4000 scf/bbl, and 0.2 to 2 LHSV to produce a tower sulfur, lower pour point lube basestock is produced with an improved viscosity index. 
     
     
       23. The process of  claim 1 , wherein the hydrocracking process is shape selective lube dewaxing, carried out at reaction conditions of 500 to 750° F., 400 to 2000 psi, 1500 to 4000 scf/bbl, and 0.2 to 2 LHSV to produce a lower sulfur, lower pour point lube product is produced with an improved viscosity index.